I have the same index.php file in each of the below folders.

languages/english
languages/english/custom
languages/english/classic

And the congratulations message is still showing. I don't have an actual custom template, I only added the index.php file to language/english/custom per the directions. I went to the template selection in the admin and the only option is the classic template which is selected.

Thanks for your help,

Robyn